Environmental enrichment

The environmental enrichment studies how the brain is affected by stimulation of its centers of perception caused by everything that surrounds (including opportunities for social interaction). The brain , in a richer and more stimulating environment, has a greater number of synapses , and the dendrites in which they reside are more complex. This effect is all the more important during the neurodevelopment phase , but still persists to a lesser degree during adulthood. This increase in synapses also generates a greater synaptic activity, which also increases the size and number of cells glial actresses of nerve impulses . The vascularization also increases and thus provides neurons and glial cells with more energy. The neuropile (neurons, glial cells and capillaries combined) thus has more expansion and makes the cerebral cortex thicker. It can also create more neurons (in rodents at least). The neuropile (neurons, glial cells and capillaries combined) thus has more expansion and makes the cerebral cortex thicker. It can also create more neurons (in rodents at least). The neuropile (neurons, glial cells and capillaries combined) thus has more expansion and makes the cerebral cortex thicker. It can also create more neurons (in rodents at least).

Research on animals shows that a more stimulating environment can help in the treatment and restoration of a wide variety of brain diseases such as senility and Alzheimer’s disease , where a deficit of stimulation handicaps cognitive development.

Research on human cases suggests that a deficit in stimulation (depressions such as, for example, being an orphan) delays and curbs cognitive development. This research has also shown that the highest levels of education (which simultaneously have cognitive stimulation by themselves and including people engaged in high-level cognitive activities) have a higher resilience for their cognitive abilities against The effects of age and dementia.

Original search
Donald O. Hebb discovered in 1947 that rats bred as domestic animals solved problems better than cage- 1 rats . This research did not, of course, analyze the brain or the positive or negative environmental factors. Research in this field will start in 1960 with the comparison of individual rats in standard cages and those placed in cages equipped with toys, ladders, tunnels and able to play together on their wheel. This will lead to discover that stimulating environments affect the activity of its cholinesterases ( enzymes ) 2 . This work led in 1962 to discover that the enrichment of the environment increases the volume of the cerebral cortex 3 . In 1964,

Also starting around 1960, Harry Harlow studied the effects of maternal and social deprivation on rhesus monkey pups (a form of deprivation of environmental stimuli). This establishes the importance of social stimulation on the development of basic cognitive skills but also on the emotional development 6 .

Synapses
Synaptic Transmission
Rats bred in an enriched environment have a thicker cerebral cortex (3.3-7%) that contains 25% more synapses. 5 , 7 The effect of an enriched environment on the brain occurs if this exposure occurs Directly after birth 8 , but declines after 5 , 7 , 9 , including during adulthood 10 . When the number of synapses increases in adults, their numbers remain high even when the adults are returned to a makeshift environment for about thirty days 10 suggests that such an increase in the number of synapses is not necessarily temporary. Nevertheless, Increase in the number of synapses was observed as decreasing with age 11 , 12 . Stimulation not only affects the synapses via neural pyramid (the main route between the neurons in the cerebral cortex) but also the stellate cells (which are usually interneurons ) 13 . This can even go as far as acting on neurons outside the brain , in the retina 14 main axis connecting neurons in the cerebral cortex) but also the stellate cells (which are usually interneurons ) 13 . This can even go as far as acting on neurons outside the brain , in the retina 14 main axis connecting neurons in the cerebral cortex) but also the stellate cells (which are usually interneurons ) 13 . This can even go as far as acting on neurons outside the brain , in the retina 14

Complexity of dendrites
The enrichment of the environment affects the complexity and length of the dendrite sector (containing synapses). The higher levels of branching dendrites are then increased 13 , 15 , and their length as in young animals 16 .

Activity and energy consumption
Synapses in animals raised by stimulating environment shows evidence of increased synaptic activity 17 . Synapses also tend to be larger 18 . This increase in energy consumption in glial cells and in local capillarity that provide synapses with increased energy.

The number of glial cells per neuron increases by 12-14% 5 , 7
There is a direct correlation between the area of influence of glial cells and increase synapse 19% 19
The glial cell volume kernel for each synapse increases 37.5% 17
The observed volume of mitochondria per neuron is 20% higher 17
The volume glial cells of the core of each neuron is greater than 63% 17
The capillary density increases 20 .
Capillaries are wider (4.35 μm compared to 4.15 μm for control values) 17
A shorter distance is created between all the actors of the neuropile and a denser capilarity (27.6 μm against 34.6 μm) 17
This energy makes it possible to link that the modifications of the neuropile are responsible for the increase of the cerebral volume, essentially by densification (the increase in number of synapses signifying in itself an increase in volume).

Stimulation of motor learning
Part of the effects of environmental enrichment is to provide complementary opportunities to acquire engine capacities. Research on the acrobatic skills of rats shows that this also leads to an increase in the number of synapses.

Maternal Transmission
The enrichment during pregnancy has effects on the fetus as accelerating the development of the retina 23 .

Neurogenesis
The enrichment of the environment can also lead to the formation of neurons (at least in rats) 24 but also a reverse neuronal loss phenomenon in the hippocampus and the memorial disorders following chronic stress 25 . However, a study shows that hippocampal neurogenesis is not necessary for the behavioral effects of the enrichment of the environment 26 . Current research shows that on the one hand we can increase our physical brain capacities at any age except probably in the neocortex but the biggest gains seem to take place until the age of 10,

Mechanism
The enrichment of the environment affects the expression of genes in the cerebral cortex and hippocampus which determines the neural structure 28 . At the molecular level , this sometimes results in increased concentration of neurotrophins NGF, NT-3 29 , 30 , and modifications in BDNF 31 , 32 . This alters the activation of 30 , 5-HT 33 cholinergic neurons and adrenergic receptors 34 . (Synaptic proteins such as synaptophysin ), and the PSD-95 / DLG4 (synaptic density on the DLG4 gene), the synaptophysin protein (four protein helix transmembrane of the membrane of synaptic vesicles storing the neuromediators, phosphorylated by tyrosine kinases) ) to the synapses 35 , 36 .L’augmentation the number of neurons may be related to changes in the vascular endothelial growth factor 37 . Everything happens as a kind of biological nexialism with elements that only serve as catalysts and others that self-train between them. Its role is still poorly understood) and PSD-95 / DLG4 (synaptic density on the DLG4 gene) to synapses 35 , 36. The increase in the number of neurons may be linked to changes in the growth factor Vascular endothelium 37 . Everything happens as a kind of biological nexialism with elements that only serve as catalysts and others that self-train between them. Its role is still poorly understood) and PSD-95 / DLG4 (synaptic density on the DLG4 gene) to synapses 35 , 36. The increase in the number of neurons may be linked to changes in the growth factor Vascular endothelium 37 . Everything happens as a kind of biological nexialism with elements that only serve as catalysts and others that self-train between them.

Resilience and Recovery
Research on rats suggests that environmental enrichment can reduce cognitive abnormalities or even improve them when they are caused by various neurological conditions and disorders:

Senility 38 , (also in dogs 39 )

Alzheimer’s disease

Huntington Chorea

Parkinson’s disease

Cerebral vascular accident (CVA)

Chronic spinal cord injury

Amblyopia

Rett Syndrome

Autism

Combating Addictions to Drugs, such as Cocaine in Pregnancy

Fetal Alcohol Syndrome

Saturnism

Emotional stress disorder maternal

Neglect of the child from child abuse to moral neglect

Humans
Although much of the research on the influence of the environment has been conducted on rodents, similar effects have been observed on primates 59 , and will thus similarly affect the human brain. In any case, direct research on human synapses is limited because it requires a histological study of the brain. Nevertheless, a link has been determined between the level of education and greater complexity of dendritic spines in the autopsy suite including the study of the brain 60 .

Location of cerebral cortex changes
MRI detects a localized expansion of the cerebral cortex after learning by people of complex tasks such as mirroring (in this case the right occipital lobe of the cortex 61 , juggling with 3 bullets (mid-temporal lobe of each Side and posterior left intraparietal sulcus 62 ) and when medical students review intensively for examinations (lateral and posterior part of the two parietal lobes of the cortex 63. Such changes in gray matter may be related to changes in the number Of synapses, due to the increase of the glial cells but also to the expansion of the vascularization made necessary by the increase of the needs of energy.

Deprivation by institutions
Children who suffer impoverishment of stimulations confinement without social interaction or without trustworthy people in orphanages poor show severe delay in the development of their cognitive and social skills 64 . 12% of them if adopted after the age of 6 months show mild to severe autism around the age of 4 years 65 . Some children in orphanages where conditions are deplorable may not even be able to pronounce intelligible words for the age of two and a half years, whereas one year in a care unit allows these children to recover almost all their capacity 66 . Disorders in other ‘

Unfortunately, such children show behaviors observed during animal experiments, showing brain differences compared to children who have lived in more stimulating classical environments. They reduced their brain activity in the prefrontal cortex , amygdala , hippocampus, temporal cortex and brain stem 68 . They also show lower development of connections between their white matter and the various other parts of the cerebral cortex, particularly the uncinate fasciculus (part of white matter that connects to the limbic system such as the hippocampus) 69 .

Similarly, the simulation of premature infants by massage accelerates the maturity of their cerebral activity observed in the EEG and their visual acuity. As is observed in animals by an enrichment of IGF-1 (peptide hormones having a chemical structure similar to that of insulin) 70 .

Cognitive Resilience and Resilience

Another source of evidence for the effect of environmental stimulation on the human brain is a person’s level of education as well as cognitive reserve (a measure of brain resistance to disorders of cognitive abilities, Being able to return quickly to the situation of stability and full recovery of his faculties after various traumas is called resilience ). Not only levels of education combined with a search for different experiences but it also correlates with people engaged in intellectual development activities. The longer a person has received education both in its variety than its depth, minus the effects of aging are felt , the risk of dementia decreases 74 , white matter activity intensifies 75 , fewer cerebrovascular accidents observed at MRI 76 , fewer cases of Alzheimer’s observed 77 , 78 , and influences the risks concussions 79 . The effects of age and the risk of dementia are also lower among people regularly performing complex cognitive tasks 80 . The decline in cognitive abilities with epilepsy may also be related to the degree of education of the person 81 . intensifies 75 , fewer strokes observed on MRI 76 fewer cases of Alzheimer observed 77 , 78 , and influences the risk of concussions 79 . The effects of age and the risk of dementia are also lower among people regularly performing complex cognitive tasks 80 . The decline in cognitive abilities with epilepsy may also be related to the degree of education of the person 81 . intensifies 75 , fewer strokes observed on MRI 76 fewer cases of Alzheimer observed 77 , 78 , and influences the risk of concussions 79 . The effects of age and the risk of dementia are also lower among people regularly performing complex cognitive tasks 80 . The decline in cognitive abilities with epilepsy may also be related to the degree of education of the person 81 . and influences the risk of concussions 79 . The effects of age and the risk of dementia are also lower among people regularly performing complex cognitive tasks 80 . The decline in cognitive abilities with epilepsy may also be related to the degree of education of the person 81 . and influences the risk of concussions 79 . The effects of age and the risk of dementia are also lower among people regularly performing complex cognitive tasks 80 . The decline in cognitive abilities with epilepsy may also be related to the degree of education of the person 81 .